Agricultural combine harvesters are used in the harvest of cereal crops, in order to harvest and thresh plants grown in a field. The threshed harvest material is subsequently processed further by a separation device. The grain obtained in the threshing and separation process is subsequently cleaned in a cleaning device and deposited in a grain tank, from which it is then finally transferred to a transport vehicle. In order to set optimally operating parameters of the threshing and separation device or of the cleaning device and/or for the predetermination of the speed of advance of the combine harvester, which determines the throughput, one uses so-called lost grain sensors that comprise impact plates with vibration sensors, which are arranged at the outlet of the respective device. Grains that impinge on the impact plate generate vibrations that are detected by the vibration sensors and evaluated by an evaluation circuit. The signals of the evaluation circuit are used for controlling a loss display and/or for the automatic setting of the speed of advance or of the operating parameters of the threshing and/or separation device and/or of the cleaning device.
Moreover, the combine harvester comprises a large number of moving parts, which can be damaged themselves, or whose bearings can be damaged, due to material defects, wear or excessive utilization. It has been proposed to detect by means of an oscillation sensor possible errors of moving parts of the harvesting machine on the basis of the vibrations caused by the defects (DE 101 00 522 A1).
In EP 1 839 478 A1, an impact sound sensor unit is described whose preliminary processing electronics can be reprogrammed for various tasks, including for use as a grain loss sensor, as a vibration sensor for monitoring the play of a bearing, or as an imbalance warning device. The impact sound sensor unit can, however, be programmed only for one application purpose at this time. In order to be able to simultaneously monitor lost grain and bearing damage, two impact sound sensor units are therefore required.
DE 10 2009 000 351 A1 describes a vibration sensor unit in whose housing a vibration sensor and a digital signal processing unit for damage monitoring as well as an analog signal processing unit for detecting impingement of a foreign body against a feed roll are incorporated.
It would be beneficial to reduce the expense required for detecting lost grains and for monitoring the moving parts of a combine harvester. It is an object of this invention to do this.
In accordance with one aspect of the invention a vibration sensor unit comprises a vibration sensor and an electronic processing circuit, which is connected in a signal transmitting manner to the vibration sensor. During operation, the signal processing circuit delivers information derived from the signals of the vibration sensor regarding the quantity of lost grains detected by the vibration sensor (particularly per unit of time). The signal processing unit outputs this result as a first initial value for further processing and/or display. At the same time the signal processing circuit examines the signals of the vibration sensor for vibrations, which may indicate potential damage to moving parts, and it delivers the result as a second initial value for further processing and/or display. In the analysis of the signals of the vibration sensor for the determination of the losses and of the machine diagnosis, one can use any desired evaluation method.
In this manner, a single vibration sensor unit simultaneously accomplishes two tasks, namely the determination of the number of lost grains per unit of time and the analysis of detected vibrations for possible signs of damage to moving parts. As a result, the expense for the steering and control of the combine harvester is decreased.
The vibration sensor and the signal processing circuit are arranged advantageously in a common housing. However, the possibility of arrangement of the vibration sensor spatially separately from the signal processing circuit also exists.
The vibration sensor is connected in particular in a vibration conducting manner to an impact plate or to an impact rod, which can be inserted in a crop flow that contains lost grains. The vibration sensor is coupled advantageously via a holder in a vibration-conducting manner to moving parts to be monitored.